Tires may have a diene rubber-based component which contains precipitated silica as a reinforcing filler. The precipitated silica is typically used in combination with a coupling agent having a moiety reactive with hydroxyl groups (e.g. silanol groups) contained on the precipitated silica and another different moiety interactive with the diene rubber to thereby promote coupling between the precipitated silica and diene rubber.
However, where the coupling agent contains low molecular weight alkoxy groups for reacting with the hydroxyl groups of the precipitated silica (e.g. one or more ethoxy groups) within the rubber composition, low molecular weight alcohols result (e.g. ethanol) as a by-product which may be objectionable in some cases during the manufacture of rubber products.
Further, the synthetic precipitated silica is somewhat incompatible with diene rubbers. In such case it has been indicated that it can be beneficial to react the precipitated silica with a hydrophobating agent (which might sometimes be referred to as a wetting agent) to hydrophobate the precipitated silica to enhance its compatibility with a diene rubber. For example, it has been suggested to hydrophobate a precipitated silica in situ within the elastomer host by addition of both an organomercaptosilane and an alkyl silane (e.g. alkoxyorganosilane). For example, see U.S. Pat. No. 4,474,908.
For example, tires may have a rubber component in which both an alkoxyorganosilyl polysulfide and an alkylsilane (e.g. alkoxysilane) are individually added to a silica-containing rubber composition to treat the silica in-situ within the rubber host with both                (A) the alkylsilane as a hydrophobating agent and        (B) a silica coupler (an alkoxyorganosilyl polysulfide compound).For example, see U.S. Pat. No. 5,780,538.        
For example, tires have been suggested which may have a component which contains a pre-hydrophobated silica in which the silica is pre-hydrophobated prior to addition to the rubber composition. For example, see U.S. Pat. No. 6,573,324.
Historically, precipitated silica aggregates are typically hydrophilic (water attracting) in nature and, in order to aid in dispersing the silica aggregates in various rubber compositions, it is sometimes desired to make the silica aggregates more hydrophobic (water repelling) in nature and therefore more compatible with the rubber.
In the aforesaid U.S. Pat. Nos. 4,474,908 and 5,780,538, a hydrophobating agent may be added to a rubber composition to combine with the silica-in-situ within the rubber host to make the silica more hydrophobic in nature. In the said U.S. Pat. No. 6,573,324, a tire is provided with a component comprised of a rubber composition which contains particulate pre-hydrophobated precipitated silica aggregates where the silica aggregates are added to, or mixed with, the rubber composition in a pre-hydrophobated form.
Historically, one object of introducing precipitated silica to a rubber composition in a pre-hydrophobated form is to improve mixing of the precipitated silica with the rubber.
For this invention, it is desired herein to provide a silanized precipitated silica (pre-silanized in a sense of being silanized prior to addition to the rubber composition) which is hydrophobated in situ within a rubber composition with at least one of epoxidized soybean oil and epoxidized rubber tree seed oil, preferably an epoxidized soybean oil.
Accordingly, it is further proposed herein to provide a tire with a component of a rubber composition which contains a pre-silanized precipitated silica which is hydrophobated in situ within the rubber composition with an epoxidized soybean oil and/or epoxidized rubber tree seed oil.
In the description of this invention, the term “phr” relates to parts by weight for a material or ingredient per 100 parts by weight elastomer(s)”. The terms “rubber” and “elastomer” are used interchangeably unless otherwise indicated. The terms “cure” and “vulcanize” are used interchangeably unless otherwise indicated.